Multi-Input Multi-Output (MIMO) technology is to improve efficiency in data transmission and reception by using multiple transmitting antennas and multiple receiving antennas instead of a single transmitting antenna and a single receiving antenna. If a single antenna is used, a receiver receives data through a single antenna path. However, if multiple antennas are used, the receiver receives data through various paths. Accordingly, speed and amount in data transmission may be increased, and coverage may be increased.
In order to increase multiplexing gain of MIMO operation, channel status information (CSI) may be fed back from a MIMO receiver to a MIMO transmitter. The receiver may determine CSI by performing channel measurement through a predetermined reference signal (RS) from the transmitter.